U.S. patent number 6,747,432 [Application Number 10/351,310] was granted by the patent office on 2004-06-08 for drive apparatus for cooling fan motor for use in vehicle.
This patent grant is currently assigned to Denso Corporation. Invention is credited to Satoshi Yoshimura.
United States Patent |
6,747,432 |
Yoshimura |
June 8, 2004 |
Drive apparatus for cooling fan motor for use in vehicle
Abstract
A cooling fan motor drive apparatus for use in vehicle is
equipped with first to fourth semiconductor switches for driving
first and second cooling fan motors upon receipt of a power supply
voltage through power supply lines. A control unit implements
control on openings and closures of the first to fourth switches to
establish first and second power supply systems between first and
second power supply lines for performing serial and parallel
operations of the first and second cooling fan motors. The control
unit closes the second and fourth semiconductor switches when the
first and second cooling fan motors are driven in series and closes
the first, second and third semiconductor switches when the first
and second cooling fan motors are drive in parallel. When an
overcurrent flows in the cooling fan motors, the control unit
conducts the serial operation of the cooling fan motors
irrespective of an operation command signal, and at the start-up of
the drive apparatus, the control unit conducts the serial operation
thereof for a predetermined time period. This drive apparatus can
be located in the vicinity of the cooling fan motors and, even if
an abnormal condition occurs temporarily, can restore to a normal
condition after the recovery.
Inventors: |
Yoshimura; Satoshi (Kariya,
JP) |
Assignee: |
Denso Corporation (Kariya,
JP)
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Family
ID: |
27606423 |
Appl.
No.: |
10/351,310 |
Filed: |
January 27, 2003 |
Foreign Application Priority Data
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Jan 31, 2002 [JP] |
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2002-023983 |
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Current U.S.
Class: |
318/599;
318/811 |
Current CPC
Class: |
F04D
27/004 (20130101); F01P 7/048 (20130101); H02P
5/68 (20130101); F01P 2005/025 (20130101); Y02B
30/70 (20130101) |
Current International
Class: |
F01P
7/00 (20060101); F01P 7/04 (20060101); F04D
27/02 (20060101); F01P 5/02 (20060101); G05B
011/28 () |
Field of
Search: |
;62/184,428,244
;165/42,43 ;318/599,800,801,811 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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56-81114 |
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Nov 1979 |
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JP |
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60-78822 |
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May 1985 |
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JP |
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60-78823 |
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May 1985 |
|
JP |
|
5-310176 |
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Nov 1993 |
|
JP |
|
8-111902 |
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Apr 1996 |
|
JP |
|
8-256404 |
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Oct 1996 |
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JP |
|
2000097026 |
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Apr 2000 |
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JP |
|
Primary Examiner: Tapoloai; William E.
Assistant Examiner: Ali; Mohammad M.
Attorney, Agent or Firm: Posz & Bethards, PLC
Claims
What is claimed is:
1. A cooling fan motor drive apparatus for use in vehicle which
drives cooling fan motors upon receipt of a power supply voltage
through power supply lines, comprising: current-carrying switching
means including first and second semiconductor switches interposed
between a first power supply line and first and second cooling fan
motors, a third semiconductor switch interposed between said second
cooling fan motor and a second power supply line and a fourth
semiconductor switch interposed between a first power supply line
side terminal of said first cooling fan motor and a second power
supply line side terminal of said second cooling fan motor; and
control means for implementing control on openings and closures of
said semiconductor switches so that said second and fourth
semiconductor switches are closed when said first and second
cooling fan motors are driven in series and said first, second and
third semiconductor switches are closed when said first and second
cooling fan motors are drive in parallel.
2. The apparatus according to claim 1, further comprising current
detecting means for outputting a current detection signal
corresponding to a current flowing in said first and second cooling
fan motors, said control means including: reference setting means
for outputting a current reference signal corresponding to a
reference current according to a condition of one of serial and
parallel operation; comparing means for comparing said current
detection signal with said current reference signal to output a
current-excess signal when said current detection signal exceeds
said current reference signal; and operation switching means for
conducting the switching from said parallel operation to said
serial operation provided that said comparing means outputs said
current-excess signal during said parallel operation.
3. The apparatus according to claim 2, wherein said comparing means
is made to output said current-excess signal when said current
detection signal continuously exceeds said current reference signal
for over a predetermined time period.
4. The apparatus according to claim 2, wherein said operation
switching means is made to conduct the switching to the condition
of said serial or parallel operation before the output of said
current-excess signal provided that said comparing means stops the
output of said current-excess signal.
5. The apparatus according to claim 4, wherein said comparing means
is made to stop the output of said current-excess signal when said
current detection signal does not continuously exceed said current
reference signal for over a predetermined time period.
6. The apparatus according to claim 1, wherein said control means
is made to conduct said serial operation of said first and second
cooling fan motors for a predetermined time period from start-up
irrespective of a command on selection between said serial and
parallel operations.
7. The apparatus according to claim 1, wherein reflux means is
connected in parallel with each of said first to fourth
semiconductor switches.
8. The apparatus according to claim 1, wherein said control means
is made to, when said power supply voltage drops to be lower than a
predetermined voltage, open said first to third semiconductor
switches and close said fourth semiconductor switch for performing
an operation for power regeneration from said cooling fan motors
toward said power supply line side.
9. A cooling fan motor drive apparatus for use in vehicle which
drives cooling fan motors upon receipt of a power supply voltage
through power supply lines, comprising: current-carrying switching
means including first and second switches interposed between a
first power supply line and first and second cooling fan motors, a
third switch interposed between said second cooling fan motor and a
second power supply line and a fourth switch interposed between a
first power supply line side terminal of said first cooling fan
motor and a second power supply line side terminal of said second
cooling fan motor; and control means for implementing control on
openings and closures of said first to fourth switches to establish
first and second power supply systems between said first and second
power supply lines for performing serial and parallel operations of
said first and second cooling fan motors.
10. The apparatus according to claim 9, further comprising current
detecting means for outputting a current detection signal
corresponding to a current flowing in said first and second cooling
fan motors, said control means including: reference setting means
for outputting a current reference signal corresponding to a
reference current according to a condition of one of serial and
parallel operation; comparing means for comparing said current
detection signal with said current reference signal to output a
current-excess signal when said current detection signal exceeds
said current reference signal; and operation switching means for
conducting the switching from said parallel operation to said
serial operation provided that said comparing means outputs said
current-excess signal during said parallel operation.
11. The apparatus according to claim 9, wherein said second and
fourth switches are closed when said first and second cooling fan
motors are driven in series and said first, second and third
switches are closed when said first and second cooling fan motors
are drive in parallel.
12. The apparatus according to claim 10, wherein, when said current
detecting means detects that the current flowing in said first and
second cooling fan motors falls into an excessive condition, said
control means controls said first to fourth switches to force said
first and second cooling fan motors into said serial operation.
13. The apparatus according to claim 9, further comprising reverse
connection switch means placed on said power supply systems so
that, if reverse connection of a battery occurs, said control means
detects the occurrence of the battery reverse connection on the
basis of an input from said first power supply line and turns off
said reverse connection switch.
14. The apparatus according to claim 9, wherein said control means
is made to force said first and second cooling fan motors to
operate in series for a predetermined time period from start-up
irrespective of a command on selection between said serial and
parallel operations.
Description
BACKGROUND OF THE INVENTION
1) Field of the Invention
The present invention relates to a cooling fan motor drive
apparatus for vehicles, which is made to drive vehicle cooling fan
motors upon receipt of a power supply voltage through a power
supply line.
2) Description of the Related Art
In a vehicle (such as a car), there is provided a cooling fan for
cooling a radiator of an engine and condenser of an air
conditioner, and so far, such a cooling fan has been rotationally
driven by a motor (for example, DC motor). FIG. 12 is an
illustration of an electrical arrangement of a drive apparatus
designed to drive two cooling fan motors in series/in parallel. In
FIG. 12, a drive apparatus 1 employs a mainstream approach, made to
drive cooling fan motors 2 and 3 in series or in parallel through
the use of three relays according to cooling capability needed.
That is, a power supply line 4 is connected through an ignition
switch (not shown) to a positive-side terminal of a battery, and
one terminal of each of exciting coils 6a, 7a and 8a of the relays
6, 7 and 8 is connected through a fuse 9 to the power supply line
4. The other terminal of each of the exciting coils 7a and 8a is
connected to the ground 12 through a water temperature switch 10
and an air conditioner high-pressure switch 11 placed in parallel
with each other. Moreover, the other terminal of the exciting coil
6a is connected through an air conditioner amplifier 13 having an
equivalent circuit illustrated and a switch 14 to the ground 12,
and further connected through the air conditioner 13 to the water
temperature switch 10 and the air conditioner high-pressure switch
11. To the air conditioner amplifier 13, a battery voltage is
supplied from the power supply line 4 through a fuse 15, and the
switch 14 takes a make-and-break action in conjunction with a
magnet clutch (not shown).
Between a power supply line 16 connected directly to the
positive-side terminal of the battery 5 and the ground 12, there
are formed a series circuit comprising a fuse 17, a relay switch
6b, a cooling fan motor 2 and a relay switch 7b (at the
on-condition of the normally-open contact) and a series circuit
comprising a fuse 18, a relay switch 8b and a cooling fan motor 3.
The normally-closed contact of the relay switch 7b is connected to
the cooling fan motor 2.
In this drive apparatus 1, the operations of the cooling fan motors
2 and 3 in the states of the water temperature switch 10, the air
conditioner high-pressure switch 11 and the switch 14 (magnet
clutch) are as shown in FIG. 13. That is, the cooling fan motors 2
and 3 come to a stop when all the switches are in the
off-condition, while they are drive in series when the switch is in
the on-state and the air conditioner high-pressure switch 11 and
the switch 14 are in the off-state, and driven in parallel when the
water temperature switch 10 or the air conditioner high-pressure
switch 11 is in the on-state.
The cooling fan motors 2 and 3 are located close to a condenser and
radiator existing in the front part of a vehicle, and for
simplifying the handling of a harness with respect to the cooling
fan motors 2 and 3 and for reducing the loss in the harness, it is
desirable that the drive apparatus is put in the vicinity of the
cooling fan motors 2 and 3. However, since the front part of a
vehicle is exposed to bad environments because of being dashed with
liquid or dust by the running of the vehicle, for installing the
drive apparatus 1 therein, there is a need to place the relays 6, 7
and 8 constituting the drive apparatus 1 in a dedicated relay box
and reinforce the sealing structure. However, since the
reinforcement of the sealing structure is costly, in the present
circumstance the drive apparatus 1 is required to be located at a
position (for example, the rear surface side of the engine room)
remote from the cooling fan motors 2 and 3 and exposed to less
liquid and dust.
In addition, since the drive apparatus 1 is composed of the fuses
9, 15, 17, 18 and the relays 6, 7, 8, for example, if the one
cooling fan motor 2 is locked during the driving of the vehicle,
the fuse 17 is fused so that the cooling fan motors 2 and 3 can be
driven only when the fuse 17 is replaced with new one. Accordingly,
once the motor lock occurs, difficulty is experienced in operating
the cooling fan motors 2 and 3 even if it is released therefrom.
Still additionally, in high-temperature and high-pressure
conditions, only the other cooling fan motor 3 is driven to produce
the lack of cooling capability, thus readily causing the
overheating or the lowering of the performance of the air
conditioner.
SUMMARY OF THE INVENTION
The present invention has been developed in consideration of the
above-mentioned situations, and it is therefore an object of the
invention to provide a cooling fan motor drive apparatus for use in
a vehicle, capable of being placed close to vehicle cooling fan
motors and, even if the cooling fan motor falls temporarily into an
abnormal condition, capable of being restored to its normal
condition after the recovery thereof.
For this purpose, according to the present invention, in a cooling
fan motor drive apparatus for use in a vehicle which drives cooling
fan motors upon receipt of a power supply voltage through a power
supply line, first to fourth semiconductor switches are provided,
and control means closes the second and fourth semiconductor
switches to establish a current-carrying path extending from a
first power supply line through the second semiconductor switch, a
second vehicle cooling fan motor, the fourth semiconductor switch
and a first vehicle cooling fan motor to a second power supply line
so that the first and second vehicle cooling fan motors are driven
in series, while the control means closes the first, second and
third semiconductor switches to establish a current-carrying path
extending from the first power supply line through the first
semiconductor switch and the first vehicle cooling fan motor to the
second power supply line and a current-carrying path extending from
the first power supply line through the second semiconductor
switch, the second vehicle cooling fan motor and the third
semiconductor switch to the second power supply line so that the
first and second vehicle cooling fan motors are driven in
parallel.
As mentioned above, this drive apparatus is designed to switch the
vehicle cooling fan motors between the serial and parallel
operations and, hence, the semiconductor switches are easily
configured into a sealed condition by means of resin molding or the
like and the size reduction is further attainable in comparison
with the conventional construction using relays. This enables the
drive apparatus to be located in the vicinity of the cooling fan
motors where the mounting space is difficult to secure and much
dashed liquid and dust exist, which simplifies the handling of the
harness with respect to the cooling fan motors and reduces the loss
in the harness. Moreover, the employment of the semiconductor
switches prevents damages and permits protection from overload,
protection from overcurrent and protection from malfunction due to
noises, and even if the cooling fan motor falls temporarily into an
abnormal condition, it can be restored to a normal operation after
the recovery from the abnormal condition.
In addition, in the drive apparatus according to the present
invention, a reference current is set in accordance with a serial
or parallel operation condition, and when a current flowing in the
cooling fan motor exceeds the reference current, an output of a
current-excess signal takes place. There is a situation that the
operation of the cooling fan motor is required to be maintained to
the utmost and it is undesirable that the operation thereof comes
to a stop during the parallel operation which particularly requires
a high cooling capability. Still additionally, considering the case
that abnormality, for example, locking, occurs in the cooling fan
motor, when the parallel operation is conducted, all the power
supply voltage is applied to a motor resistor so that there is a
possibility that an extremely large current flows, while at the
serial operation the cooling fan motor taking an non-locked
condition undertakes the power supply voltage so that the current
is relatively suppressible. Therefore, when the switching from the
parallel operation to the serial operation is made provided that a
current-excess signal is outputted at the parallel operation, it is
possible to continue the cooling while maintaining the cooling
capability to some extent even in the case of the occurrence of
abnormality.
Moreover, in the drive apparatus according to the present
invention, when a current detection signal continues for over a
predetermined time period and exceeds a current reference signal, a
current-excess signal is outputted to make the switching from the
parallel operation to the serial operation. This prevents the
actually unnecessary switching to the serial operation from being
made in a case in which an excessive rush current flows temporarily
due to the switching from the serial operation to the parallel
operation or in a case in which an erroneous current-excess signal
is outputted due to noises or the like, thus achieving stable
operations.
Still moreover, in the drive apparatus according to the present
invention, the switching to the serial/parallel operation condition
before the output of the current-excess signal is made provided
that the output of the current-excess signal comes to a stop, which
secures the cooling capability to the utmost in the case of a high
cooling capability being required.
Furthermore, in the drive apparatus according to the present
invention, when the current detection signal continues for over a
predetermined time period and does not exceed the current reference
signal, the output of the current-excess signal is stopped and the
switching to the serial/parallel operation condition before the
output of the current-excess signal is made, thereby preventing the
hunting phenomenon that the serial operation and the parallel
operation are frequently conducted repeatedly.
Still furthermore, in the drive apparatus according to the present
invention, the control means conducts the serial operation only for
a predetermined time period at the start-up irrespective of a
selection command for the serial/parallel operation to produce
speed electromotive forces in the first and second cooling fan
motors and then makes the switching to the parallel operation
according to the selection command, thus reducing the rush current
at the start-up in comparison with the start-up in the parallel
condition.
In addition, in the drive apparatus according to the present
invention, reflux means is connected to the first to fourth
semiconductor switches in parallel, thus suppressing the occurrence
of the surge voltage occurring at the switching of the
semiconductor switch from the on-condition to the
off-condition.
Still additionally, in the drive apparatus according to the present
invention, in a case in which a rotational force is given to the
cooling fan motor while it catches wind, for example, in a state
where the vehicle is running and the power supply voltage drops
below a predetermined voltage, when the control means opens the
first to third semiconductor switches and closes the fourth
semiconductor switch so that a current flows through a path
extending from the second power supply line through the first
cooling fan motor, the fourth semiconductor switch, the second
cooling fan motor and the reflux means connected in parallel with
the second semiconductor switch to the first power supply line to
accomplish the regeneration of power on the power supply line side.
This improves the power balance.
BRIEF DESCRIPTION OF THE DRAWINGS
Other objects and features of the present invention will become
more readily apparent from the following detailed description of
the preferred embodiments taken in conjunction with the
accompanying drawings in which:
FIG. 1 is an illustration of electric arrangements of a drive
apparatus according to a first embodiment of the present invention
and peripheral devices;
FIG. 2 is an illustration of an electric arrangement of the drive
apparatus, showing a concrete circuit arrangement of a control
IC;
FIG. 3 is an illustration of an on/off state of a MOS transistor
and an operating state of a fan motor when a current-excess signal
Sk shows an L level;
FIG. 4 is a timing chart of serial/parallel operations;
FIG. 5 is an illustration of a current detection signal Sh and a
current reference signal Sj in normal and abnormal conditions;
FIG. 6 is a flow chart showing an operation of an operation control
circuit according to a second embodiment of the present
invention;
FIG. 7 is a timing chart of serial/parallel operations;
FIG. 8 is an illustration of an electric arrangement of a drive
apparatus according to a third embodiment of the present invention
and peripheral devices;
FIG. 9 is an illustration of an on/off state of a MOS transistor
and an operating state of a fan motor when a current-excess signal
Sk shows an L level;
FIG. 10 is an illustration of a generated voltage Vm and a
regenerative current Im with respect to a speed of rotation of a
fan motor;
FIGS. 11A and 11B are illustrations of an electric arrangement of a
drive apparatus according to a fourth embodiment of the present
invention and peripheral devices;
FIG. 12 is an illustration of an electric arrangement of a drive
apparatus according to a conventional technique; and
FIG. 13 is an illustration of an operation of a cooling fan motor
at respective states of switches of the drive apparatus shown in
FIG. 12.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
(First Embodiment)
Referring to FIGS. 1 to 5, a description will be given hereinbelow
of a first embodiment of the present invention.
FIG. 1 is an illustration of electric arrangements of a drive
apparatus for a cooling fan motor for use in a vehicle, and
peripheral devices. In FIG. 1, designated at reference numeral 21
is a drive apparatus according to the first embodiment, and first
and second vehicle cooling fan motors (each of which will be
referred to hereinafter as a "fan motor") 22 and 23 to be driven by
the drive apparatus 21 are DC motors which are for driving cooling
fans 22a and 23a to cool an radiator 24 of an engine and a
condenser 25 of an air conditioner located in a front part of a
vehicle.
The drive apparatus 21 is placed in the vicinity of the fan motors
22 and 23 in a state resin-molded and dustproof/waterproof-sealed,
and the fan motors 22 and 23 are connected between terminals 21a
and 21b of the drive apparatus 21 and between terminals 21c and 21d
thereof. A power supply terminal 21e of the drive apparatus 21 is
connected through a power supply line 27 (corresponding to a first
power supply line) with a fuse 26 to the positive-side terminal of
a battery 28, while a power supply terminal 21f thereof is
connected to the negative-side terminal of the battery 28 and
further to the ground or earth 29 (corresponding to a second power
supply line), thereby supplying a battery voltage VB2 to between
the power supply terminals 21e and 21f at all times.
A control power supply terminal 21g is connected through a fuse 30
and an ignition switch (not shown) to the positive-side terminal of
the battery 28. Therefore, between the power supply terminals 21g
and 21f, the battery voltage VB1 is supplied only for the time
period of the closure of the ignition switch. The fuses 26 and 30
to be used in this arrangement are not for protecting the drive
apparatus 21 from motor locking, motor overload or the like, but
for, when the drive apparatus 21 itself falls into troubles or
faults, such as short-circuit of semiconductor switches, preventing
the enlargement of the troubles.
The engine control ECU (Electronic Control Unit) 31 is made to
receive an air conditioner operation signal Sa from an air
conditioner ECU (not shown) to produce an operation command signal
Sb for the fan motors 22 and 23 on the basis of the operation
signal Sa, a temperature of engine coolant (cooling water) and
others. This operation command signal Sb is given to a terminal 21h
of the drive apparatus 21. The ECU 31 operates on the battery
voltage VB1 supplied through the ignition switch and the fuse
32.
The drive circuit 21 is constructed in the form of a hybrid IC
composed of a control IC 33 (corresponding to control means), a
switching circuit 34 (corresponding to current-carrying path
switching means) and a current detection resistor 35 (corresponding
to current detecting means). Of these, the switching circuit 34 is
made up of N-channel power MOS transistors 36 to 39 (first to
fourth semiconductor switches) which function as switch means, and
between the drain and source of each of these MOS transistors 36 to
39, the corresponding one of diodes 36a to 39a (parasitic diodes
built in the MOS transistors 36 to 39) is connected, which uses the
drain side as cathode and functions as reflux means.
That is, the drains and sources of the MOS transistors 36, 37, 38
and 39 are connected between the terminals 21e and 21a, between the
terminals 21e and 21c, between the terminals 21d and 21b and
between the terminals 21a and 21d, respectively. The terminal 21b
is connected through the resistor 35 to the terminal 21f.
Secondly, referring to FIG. 2, a description will be given
hereinbelow of an electric arrangement of the control IC 33. In
FIG. 2, the peripheral circuits of the drive apparatus 21 are
omitted except the fan motors 22 and 23.
The control IC 33 is made up of a control power supply circuit 40,
an oscillation circuit 41, a boosting circuit 42, an operation
control circuit 43 (corresponding to operation switching means), an
overcurrent detection circuit 44 and a drive circuit 45. In this
configuration, the control power supply circuit 40 is a series
regulator for generating a control power supply voltage Vcc (for
example, 5V) from the battery voltage VB1 supplied through the
ignition switch, with the control power supply voltage Vcc being
fed to the oscillation circuit 41, the operation control circuit 43
and the overcurrent detection circuit 44.
The oscillator circuit 41 is for generating a pulse signal with a
predetermined frequency, and the boosting circuit 42 is a charge
pump circuit for generating a step-up voltage Vcp of approximately
24V from a battery voltage VB2 (for example, 14V) through the use
of the pulse signal. The drive circuit 45 is for outputting drive
signals Sd to Sg to the MOS transistors 36 to 39, respectively, on
the basis of an operation signal Sc (described later) inputted from
the operation control circuit 43. These drive signals Sd to Sg are
produced using the step-up voltage Vcp and are a high voltage
enough to turn on the MOS transistors 36 to 39. However, in a case
in which the MOS transistors 36 to 39 is of a P-channel type, the
boosting circuit 42 becomes unnecessary. Moreover, it is also
acceptable that, for the drive signals Sg and Sf, the battery
voltage VB1 is used in place of the step-up voltage Vcp.
The overcurrent detection circuit 44 is composed of a differential
amplification circuit 46, a reference voltage setting circuit 47
(corresponding to reference setting means) and a comparison circuit
48 (corresponding to comparing means). The differential
amplification circuit 46 makes differential amplification on a
voltage across the resistor 35 developing in proportion to currents
(motor current) flowing in the fan motors 22 and 23, and outputs
the amplified voltage as a current detection signal Sh. It is
composed of an operational amplifier 49, resistors 50 to 53 and a
capacitor 54. Owing to the employment of the capacitor 54, the
differential amplification circuit 46 also function as a low-pass
filter to remove noises superimposed on the voltage across the
resistor 35.
The reference voltage setting circuit 47 is for outputting a
current reference signal Sj having a voltage value corresponding to
a reference current in accordance with a switching signal Si given
from the operation control circuit 43 in conjunction with a
serial/parallel operation state. Concretely, the reference voltage
setting circuit 47 generates divided voltages Vd1 and Vd2 of the
battery voltage VB1 through the use of resistors 55, 56 and 57
connected in series, and when the switching signal Si is at the H
(High) level (parallel operation), outputs the divided voltage Vd1
through a switching circuit 58, while, when the switching signal Si
is at the L (Low) level (serial operation), outputting the divided
voltage Vd2 through the switching circuit 58.
The comparison circuit 48 compares a current detection signal Sh
with a current reference signal Sj to output a current-excess
signal Sk to the operation control circuit 43. An non-inverting
input terminal of a comparator 59 is connected through a resistor
60 to an output terminal of the operational amplifier 49 while an
inverting input terminal thereof is connected through a resistor 61
to the switching circuit 58. An output terminal of the comparator
59 outputting a comparison signal Sl is connected through a delay
circuit 62 to a set terminal S of an R-S flip flop 63 and further
connected through an inverter 64, a delay circuit 65 and an OR gate
66 to a reset terminal R of the R-S flip flop 63. An output
terminal Q of the R-S flip flop 63 outputs the above-mentioned
current-excess signal Sk.
The delay circuit 62 is made to switch an output signal from the L
level to the H level when the inputted comparison signal Sl turns
from the L level to the H level and this H level continues for a
time period T1. Likewise, the delay circuit 65 switches an output
signal from the L level to the H level when the inverted signal of
the inputted comparison signal turns from L level to the H level
and this H level continues for a time period T2. In this
connection, the aforesaid OR gate 66 is made to receive a reset
signal Sm which turns temporarily to the H level when the ignition
switch is turned on.
The operation control circuit 43 is made to determine the operating
conditions of the fan motors 22 and 23, i.e., stop, serial
operation and parallel operation thereof, on the basis of the
operation command signal Sb inputted from the ECU 31, the
current-excess signal Sk inputted from the overcurrent detection
circuit 44 and the battery voltage VB1 detected by a power supply
voltage monitoring circuit (not shown). Moreover, the operation
control circuit 43 outputs an operation signal Sc representative of
the operation condition determined, and outputs a switching signal
Si corresponding to the operation condition.
Furthermore, the operations of the drive apparatus 21 according to
this embodiment will be described hereinbelow with reference to
FIGS. 3 to 5.
FIG. 3 is an illustration of on/off states of the MOS transistors
36 to 39 in a case in which the current-excess signal Sk assumes
the L level, and the operating conditions of the fan motors 22 and
23. The operation control circuit 43 sets the operation signal Sc
to "stop" when the control battery voltage VB1 is lower than 8V and
the operation command signal Sb is constant at 0V, and the drive
circuit 45 turns off all the MOS transistors 36 to 39, so the fan
motors 22 and 23 come into the non-energized conditions and the
cooling fans 22a and 23a stop if receiving no external force such
as wind.
On the other hand, in a case in which the battery voltage VB1 is in
a normal voltage range, i.e., equal to or higher than 8V and equal
to or lower than 16V, the operation control circuit 43 sets the
operation signal Sc to "serial operation" when the operation
command signal Sb is a 250 Hz, 50% duty pulse signal, and sets the
operation signal Sc to "parallel operation" when the operation
command signal Sb is constant at 5V. In the case of the "serial
operation", the drive circuit 45 sets drive signals Se and Sg at
the step-up voltage Vcp and turns on the MOS transistors 37 and 39.
At this time, a current-carrying path develops, which extends from
the terminal 21e through the MOS transistor 37, the fan motor 23,
the MOS transistor 39, the fan motor 22 and the resistor 35 to the
terminal 21f, so that the fan motors 22 and 23 come into the serial
operation condition.
Furthermore, in the case of the "parallel operation", the drive
circuit 45 sets the drive signals Sd, Se and Sf at the step-up
voltage Vcp and turns on the MOS transistors 36, 37 and 38. At this
time, a current-carrying path comes out, which extends from the
terminal 21e through the MOS transistor 36, the fan motor 22 and
the resistor 35 to the terminal 21f, and a current-carrying paths
develops, which extends from the terminal 21e through the MOS
transistor 37, the fan motor 23, the MOS transistor 38 and the
resistor 35 to the terminal 21f, thereby operating the fan motors
22 and 23 in parallel. In either case, all the current flowing
through the fan motors 22 and 23 passes through the resistor 35. In
this connection, at the switching among the operating conditions,
the currents flowing due to the speed electromotive forces of the
fan motors 22 and 23 are refluxed to the diodes 36a to 39a, thereby
suppressing the occurrence of the surge currents.
Still furthermore, a description will be given hereinbelow of an
operation to be conducted in a case in which an overcurrent
flows.
In a timing charge of FIG. 4, when the ignition switch is turned on
at the time t1, a reset signal Sm is inputted to the OR gate 66 and
a current-excess signal Sk is reset to the L level. Under the
condition that the temperature of the coolant is low and the
compressor pressure of the air conditioner is low, the ECU 31
outputs an operation command signal Sb comprising a pulse signal.
In this case, the operation control circuit 43 sets an operation
signal Sc to "serial operation" in accordance with the operation
command signal Sb and sets a switching signal Si at the L level,
whereby the fan motors 22 and 23 are driven in a serially operating
condition, and a current reference signal Sj for the serial
operation is set by the switching circuit 58. Incidentally,
although not shown in FIG. 4, at the start-up, there arises that a
rush current occurs so that a current detection signal Sh increases
temporarily.
For the period from the time t2 to the time t3, the fan motors 22
and 23 rotate normally, and the cooling of the radiator 24 and the
condenser 25 takes place with a relatively low cooling capability.
In this case, the current detection signal Sh corresponding to the
detection current is lower than the current reference signal Sj
corresponding to a reference current, and a comparison signal Sl
and a current-excess signal Sk turn to the L level.
On the other hand, assuming that the fan motor 22 stops (locked)
for the period from the time t3 to the time t4, the motor current
increases so that the current detection signal Sh exceeds the
current reference signal Sj. FIG. 5 is an illustration of the
magnitudes of the current detection signal Sh with respect to the
current reference signal Sj at the battery voltage VB2 in the
normal and abnormal (motor-locked) conditions. Because Sh>Sj,
the comparison signal Sl switches from the L level to the H level,
and owing to the effect of the delay circuit 62, the current-excess
signal Sk also turns to the H level after the delay of a time
period T1 with respect to the time t3.
However, since the fan motor 23 rotating normally accepts the
battery voltage VB2, the motor current does not exceed the possible
maximum current value flowing through the fan motor 23 and the MOS
transistors 37 and 39. Therefore, the operation control circuit 43
continues the serial operation in this state. When the fan motor 22
is released from the locked condition at the time t4, the
comparison signal Sl becomes the L level, and owing the effect of
the delay circuit 65, the current-excess signal Sk also returns to
the L level after the delay of a time period T2.
Following this, at the time t5, when a water temperature switch
indicative of a rise of the coolant temperature turns on or when a
high-pressure switch representative of a rise of the compressor
pressure turns on, the ECU 31 outputs an operation command signal
Sb constant at 5V. The operation control circuit 43 sets the
operation signal Sc to "parallel operation" in accordance with the
operation command signal Sb and, at the same time, changes the
switching signal Si to the H level. In this way, the fan motors 22
and 23 are switched into the parallel operation condition, and the
current reference signal Sj for the parallel operation is set by
the switching circuit 58. Incidentally, although not shown in FIG.
4, at the switching, a rush current can occur to temporarily
increase the current detection signal Sh.
For the period from the time t5 to the time t6, the fan motors 22
and 23 rotate normally and the radiator 24 and the condenser 25 are
cooled with a relative high cooling capability. In this case, the
current detection signal Sh is lower than the current reference
signal Sj, and the comparison signal Sl and the current-excess
signal Sk turn to the L level.
On the other hand, assuming that the fan motor 22 comes to a stop
(locked) for the period from the time t6 to the time t8, the motor
current increases so that the current detection signal Sh becomes
larger than the current reference signal Sj. Thus, the comparison
signal Sl switches from the L level to the H level, and owing to
the effect of the delay circuit 62, the current-excess signal Sk
turns to the H level at the time t7 after the delay of the time
period T1 from the time t6.
When the current-excess signal Sk becomes the H level during the
parallel operation, the operation control circuit 43 makes the
switching to the serial operation regardless of the operation
command signal Sb to continue the cooling by the cooling fan 23a.
This is because of the protection of the fan motor 22 and the drive
apparatus 21 from an excessive current. That is, if the fan motor
22 falls into a motor-locked condition during the parallel
operation, a motor current approximate to the aforesaid maximum
current value flows unlike the case of the serial operation.
Following this, when the fan motor 22 is released from the locked
condition at the time t8, the comparison signal Sl turns to the L
level, and owing to the operation of the delay circuit 65, the
current-excess signal Sk returns to the L level at the time t9
after the delay of the time period T2 therefrom. When the
current-excess signal Sk becomes the L level, the operation control
circuit 43 resumes the parallel operation in accordance with the
operation command signal Sb. Incidentally, although the above
description relates to the case of the fan motor 22 falling into a
locked condition, a similar operation is conducted also in a case
in which the fan motor 23 falls into a locked condition.
As described above, since the drive apparatus 21 according to this
embodiment is equipped with the switching circuit 34 whereby the
two fan motors 22 and 23 can be driven in series and in parallel
through the use of the combination of the MOS transistors 36 to 39,
a sealing structure can easily be made by means of resin molding
and the size reduction is feasible as compared with the
conventional structure using relays, which enables the drive
apparatus 21 to be located in the vicinity of the fan motors 22 and
23 (near the front part of a vehicle) hardly allowing the formation
of a mounting space and dashed with liquid or dust and which
simplifies the handling of a harness with respect to the fan motors
22 and 23 and reduces the loss in the harness.
To the MOS transistors 36 to 39, the reflux diodes 36a to 39a are
connected, which suppresses the occurrence of a surge voltage.
Moreover, the employment of the semiconductor switches enables
overload protection, overcurrent protection and malfunction
protection stemming from noises, due to non-breakdown, and even if
an abnormal condition such as a motor-locked state occurs
temporarily in the fan motors 22 and 23, the restoration to the
normal condition is possible after the recovery from that abnormal
condition.
When the current-excess signal Sk comes into the H level due to an
overcurrent while the fan motors 22 and 23 are driven in parallel
in order to provide a high cooling capacity, the drive apparatus 21
performs the switching from the parallel operation to the serial
operation and, hence, can continue the cooling while securing the
cooling capability in some degree even if an abnormality occurs.
This can minimize the rise of coolant temperature or the drop of
cooling performance.
In addition, since the current-excess signal Sk is switched to the
H level to conduct the switching from the parallel operation to the
serial operation when the current detection signal Sh continuously
exceeds the current reference signal Sj for over the time period
T1, it is possible to prevent the switching to the serial operation
due to the occurrence of temporary overcurrent or noise originating
from the switching to the parallel operation, thus achieving the
stabilization of the operations. Still additionally, when the
current detection signal Sh does not reach the current reference
signal Sj for over the time period T2, the current-excess signal Sk
turns to the L level to perform the switching from the serial
operation to an operation according to the operation command signal
Sb, thus preventing the hunting phenomenon that the serial
operation and the parallel operation are repeatedly conducted at
frequent intervals.
(Second Embodiment)
Secondly, referring to FIGS. 6 and 7, a description will be given
hereinbelow of a second embodiment of the present invention. A
drive apparatus according to this embodiment features that a start
processing circuit is added to the operation control circuit 43 in
order to reduce the motor rush current at the start-up.
FIG. 6 is a flow of processing to be implemented by the operation
control circuit made in the form of a hardware. In response to the
turning-on of the ignition switch, the operation control circuit
waits continuously in the intact state while the operation command
signal Sb is 0V (stop command) (step R1). If the operation command
signal Sb varies to a pulse signal (serial operation command) or 5V
(parallel operation command), the operation control circuit
conducts the serial operation for a time period indicative of a
start-up time period Td irrespective of the serial/parallel
operation command (step R2), and after the completion of this
serial operation, implements the parallel operation (steps R3 and
R4) or the serial operation (steps R3 and R5) in accordance with
the operation command signal Sb. The operation control circuit
makes a decision as to whether or not the operation command signal
Sb varies to 0V during these serial/parallel operations (step R6).
If it does not reach 0V, the step R3 follows, and if it becomes 0V,
the operational flow returns to the step R1.
FIG. 7 is a timing chart showing the above-mentioned processing
contents. After the turning-on of the ignition switch, when the
operation command signal Sb indicates the serial operation at the
time t10, the operation control circuit conducts the serial
operation for a time period, including the aforesaid start-up time
period Td, up to the time t11. On the other hand, when the command
to the parallel operation is issued through the operation command
signal Sb at the time t12, the operation control circuit once
conducts the serial operation for a time period from the time t12
to the time t13 at which the start-up time period Td elapses and
subsequently switches it to the parallel operation in accordance
with the operation command signal Sb. In this case, the start-up
time period Td is set to a time period (for example, 2 to 5
seconds) during which a current once increased lowers to the
vicinity of the steady-state current.
Since no speed electromotive force develops in the fan motors 22
and 23 which is in the stopping condition, when a voltage is
applied to the fan motors 22 and 23, a rush current larger than a
current flowing in a steady state flows, and this rush current
increases as the applied voltage becomes higher. In FIG. 7, the
current detection signal Sh indicated by a broken line in the time
period from the time t12 to the time t13 shows a current flowing in
the case of the start-up in the parallel condition.
According to this embodiment, the operation control circuit
conducts the serial operation for the start-up time period Td at
the start-up regardless of the serial/parallel operation command
based on the operation command signal Sb for generating a speed
electromotive force and then performing the switching to the
parallel operation in accordance with the operation command signal
Sb, thus reducing the rush current at the start-up in comparison
with the case of the start-up in the parallel condition. In
consequence, it is possible to stem the drop of the battery
voltages VB1 and VB2 at the start-up of the fan motors 22 and 23,
thus reducing the influence of the power supply voltage variation
on other devices working on the basis of the battery voltages VB1
and VB2.
(Third Embodiment)
Furthermore, referring to FIGS. 8 to 10, a description will be
given hereinbelow of a third embodiment of the present
invention.
FIG. 8 is an illustration of an electric arrangement of a drive
apparatus for fan motors and peripheral devices. In FIG. 8, the
same reference numerals as those used above designate the same
components. A drive apparatus 67, shown in FIG. 8, is equipped with
an arrangement for regenerating generated energy of the fan motors
22 and 23 in a case in which the cooling fans 22a and 23a rotate
while catching wind during running. An ECU 68 monitors the battery
voltage VB1, and if the battery 28 is not in a fully charged
condition and, for example, the vehicle speed exceeds 80 km/h, a
power generation command signal Sn to be given to an terminal 21i
of the drive apparatus 67 is set at 5V. Under conditions other than
the aforesaid condition, the power generation command signal Sn is
set at 0V.
A control IC 69 of the drive apparatus 67 operate the fan motors 22
and 23 as shown in FIG. 9 in accordance with a level of the power
generation command signal Sn. That is, in a case in which the power
generation command signal Sn assumes 0V, the same operation as that
shown in FIG. 3 is conducted, and in a case in which the power
generation command signal Sn is at 5V, a power generation operation
is conducted when the battery voltage VB1.gtoreq.8V and the
operation command signal Sb is at 0V. In this power generation
operation, the control IC 69 sets a drive signal Sg to the step-up
voltage Vcp (the battery voltage VB1 is also acceptable) and turns
on only the MOS transistor 39.
When the vehicle runs and catches wind from the front side, the
wind due to the running successively passes through the condenser
25 and the radiator 24 to contribute to the cooling thereof and
then reaches the cooling fans 22a and 23a. If the cooling fans 22a
and 23a receive a rotational force stemming from the wind due to
the running, this rotational energy is converted into power
generation energy as mentioned below. In the above-mentioned power
generation operation, a current-carrying path is established which
extends from the terminal 21f through the resistor 35, the fan
motor 22, the MOS transistor 39, the fan motor 23 and the diode 37a
to the terminal 21e, and the regeneration of the power generation
energy from the fan motors 22 and 23 is made with respect to the
battery 28 in a state where the fan motors 22 and 23 are connected
in series. The reason that the fan motors 22 and 23 are connected
in series is that there is a need to use a higher power generation
voltage Vm for charging the battery 28.
FIG. 10 is an illustration of characteristics of a power generation
voltage Vm (V) and a regenerative current Im (A) relative to a
speed of rotation of the fan motors 22 and 23, where the battery
voltage VB2 (VB1) is at 14V. On the horizontal axis indicative of
speeds of rotation, the corresponding vehicle speeds (km/h) are
written additionally. The power generation voltage Vm between the
terminals 21c and 21d rises at an approximately constant gradient
as the vehicle speed increases and the speed of rotation of the fan
motors 22 and 23 increases. In addition, when the power generation
voltage Vm reaches the battery voltage VB2 (14V) at a vehicle speed
of 80 km/h, the regenerative current Im starts to flow through the
above-mentioned current-carrying path, and, thereafter, the power
generation voltage Vm assumes an approximately constant value. The
regenerative current Im increases as the vehicle speed increases
and the speed of rotation of the fan motors 22 and 23 rises. The
output of a power generation command from the ECU 68 when the
vehicle speed exceeds 8-km/h is based on this power generation
characteristic shown in FIG. 10.
As described above, the drive apparatus 67 according to this
embodiment is designed to regenerate the power generation energy by
connecting the fan motors 22 and 23 in series under the conditions
that the battery 28 is not in the fully charged condition and the
vehicle speed exceeds a predetermined value and the cooling fans
22a and 23a are rotating while catching wind due to the running of
the vehicle, thus improving the power balance between the power
generation and the power consumption in the vehicle and further
charging the battery 28. In particular, since the vehicle is
susceptible to stronger wind with the running unlike others
catching natural wind, the cooling fans 22a and 23a catching the
wind due to the running can easily attain their high rotation
speed, thereby regenerating large power generation energy from the
fan motors 22 and 23.
This embodiment can also offers the same effects of the first
embodiment.
(Fourth Embodiment)
Still furthermore, referring to FIGS. 11A and 11B, a description
will be given hereinbelow of a fourth embodiment of the present
invention. A feature of the forth embodiment is the employment of
an arrangement for protection against reverse connection of a
battery in addition to the arrangement of the drive apparatus 21
shown in FIG. 1.
FIG. 11A is an illustration of an electric arrangement of a drive
apparatus for fan motors and peripheral devices, and FIG. 11B is an
illustration of an arrangement of a control IC of the drive circuit
shown in FIG. 11B. In FIGS. 11A and 11B, the same reference
numerals as those used above designate the same or corresponding
components.
A drive apparatus 70, shown in FIG. 11A, comprises, in addition to
the control IC 33, the switching circuit 34 and the current
detection resistor 35, a reverse connection switch 73 which
constitutes a battery reverse connection preventing means.
Moreover, as shown in FIG. 11B, the control IC 33 is made up of, in
addition to the control power supply circuit 40, the oscillation
circuit 41, the boosting circuit 42, the overcurrent detection
circuit 44 and the drive circuit 45, an operation control circuit
43' (corresponding to the operation control circuit 43 in the
above-described first embodiment) with input processing means. The
operation control circuit 43' with input processing means is
connected to the terminal 21e coupled to the battery 28 in order to
monitor the input (corresponding to the battery voltage) at the
terminal 21e for outputting a signal Sx through the drive circuit
45 to the reverse connection switch 73 when needed (in the case of
the occurrence of battery reverse connection).
The reverse connection switch 73, taking the on state in the normal
condition (under the control of the control IC 33), is placed in
any portion on the path extending from the battery 28 through the
semiconductor switch 36, the semiconductor switch 39 and the
semiconductor switch 38 to the ground. The reverse connection
switch 73 is also connected to the control IC 33 to be operated in
accordance with the signal Sx outputted from the control IC 33.
That is, the operation control circuit 43' with input processing
means makes a decision on the occurrence of the battery reverse
connection on the basis of an input at the terminal 21e coupled to
the battery 28. If a battery reverse connection occurs, the
operation control circuit 43' outputs the reverse connection signal
Sx through the drive circuit 45 to the reverse connection switch 73
so that the reverse connection switch 73 on the current-carrying
path to the fan motors 22 and 23 is switched to the off state.
(Other Embodiments)
It should be understood that the present invention is not limited
to the above-described embodiments shown in the illustrations, and
that it is intended to cover all the following changes and
modifications. For example, an arrangement based on a combination
of the second and third embodiment is also acceptable, and the
delay circuits 62 and 65 are also employable as needed. In
addition, a brushless DC motor is also acceptable as the vehicle
cooling fan motor, and an IGBT or a bipolar transistor is also
acceptable as the foregoing semiconductor switches.
* * * * *